When the lid is closed the only remaining buttons on the Pandora are the L + R shoulder buttons and the power slider.
Applications operating in this mode should utilize that few available buttons!
Example for button utilization in a audio playback software:
L + R at once: Toggle Play/Pause
L hold: fast backward
R hold: fast forward
L click: jump to previous song
R click: jump to next song
L double click: jump to previous album/artist
R double click: jump to next album/artist